Clogging of water pipes, toilets and the like is a common problem and there are many kinds of simple suction devices available for unclogging same. The most common device consists of a solid handle and a hemispherical suction cup, the device being operated by placing the suction cup directly on the opening of a pipe or the like and pressing down repeatedly on the handle. Because there is no air passage between the handle and the suction cup, air trapped and compressed within the suction cup has to escape from the edge of the suction cup when the cup is pressed down. In order to improve the suction effect of the known devices, Applicant has developed a novel piston plunger.